The saying goes that "you are what you eat." And, according to new research, if you eat a lot of fast food, what you might be is depressed. Published in the journal Public Health Nutrition, the study found that people who eat fast food and commercial baked goods are 51 percent more likely to develop depression than those who eat little to none.
For about six months, researchers from the University of Las Palmas de Gran Canaria and the University of Granada surveyed 8,964 participants who had never been diagnosed with depression or taken antidepressants. "Junk food" was defined as eating commercial baked goods (such as cakes, croissants, and doughnuts) and fast food (such as hamburgers, hot dogs, and pizza). Researchers found that the more junk food people ate, the stronger the link to depression was.
Despite the association, junk food was not the only possible cause of depression. The study showed that those who ate the most fast food and commercial baked goods were also more likely to be single, less active, and have poor dietary habits, which includes eating less fruit, nuts, fish, vegetables, and olive oil. Those who were depressed were also more likely to be smokers and work more than 45 hours per week, according to the study.
This isn't the first time highly processed foods have been linked to depression or low mood, says Mary Hartley, a registered dietitian in New York City. A 2009 study published in the British Journal of Psychiatry found similar results.
"I have not seen a study in support of junk food (empty calories) and mental health, although people should realize that minimally processed foods (bagged salads, roasted nuts, canned tuna, frozen fruit, nut butters, tomato sauce, etc.) are fine," Hartley says. "But people who have poor-quality diets often have subclinical deficiencies of essential nutrients. The body needs nutrients to make neurotransmitters, and so, sure, nutrient deficiencies may have a role in some mental and behavioral disorders."
In fact, research has shown that certain nutrients have a preventative role in depression, she says. For example, omega-3 fatty acids, vitamin C, vitamin E, iron, magnesium and zinc have all been linked to depression or its prevention. In another study, foods eaten when following a Mediterranean Diet were linked to a lower risk of depression.
"Foods rich in the B-vitamins, folic acid, such as lentils, bean, spinach, oranges, asparagus, avocado, seeds, tomatoes, and fortified cereals, might help," Hartley says. "And foods high in vitamin D may help, too. Those include fatty fish, egg yolks, and milk. As well as the sun itself, the most important source of vitamin D."
The bottom line is that an all-around balanced diet is good for the mood. And an unhealthy diet? Well, it's good to avoid for a number of reasons.
"No one should eat junk food on a regular basis," Hartley says. "And, people who are depressed should get the help they need in order to make an extra effort to take better care of their physical health: eat a balanced wholesome diet, get physical activity, no smoking or excess alcohol, get enough sleep, etc."
Have you noticed a connection between eating junk food and mood? Tell us about it!
Jennipher Walters is the CEO and co-founder of the healthy living websites FitBottomedGirls.com and FitBottomedMamas.com. A certified personal trainer, lifestyle and weight management coach and group exercise instructor, she also holds an MA in health journalism and regularly writes about all things fitness and wellness for various online publications.